Continuous casting machine

ABSTRACT

The machine includes a mold to be inserted in a frame-type mold table, a strand guide connected downstream of the mold and a mold oscillator supporting and moving the mold table. In order to minimize restranding times during section change through the formation of a section-related machine head, a first strand guide segment is detachably integrated in a strand guide segment connected downstream and a mold stirrer is supported on the second strand guide segment.

BACKGROUND OF THE INVENTION

The invention relates to a continuous casting machine, particularly to abillet or bloom caster, with a mold to be inserted in a frame-type moldtable and a strand guide connected downstream of the mold and comprisedof several strand guide segments carrying strand guide rollers and witha mold oscillator supporting and moving the mold table.

Continuous casting machines generally serve to cast strands of differentcross-sectional dimensions within a minimum restranding time andrequiring a minimum number of spare parts. Large-section strands arecast with adjustable plate molds, whereas for strands with billet crosssections and partly for strands with bloom cross sections tubular moldsare used which are exchanged upon section change. Exchanging the moldalone is not sufficient since there is still a liquid zone inside thestrand and the hot strand shell, still being thin and easily deformable,must be supported without misalignment particularly after exiting themold, so the strand guide segment connected downstream must also beexchanged.

A continuous casting machine of this type is already known from DE-A 1957 689, where the mold, the mold table carrying the mold, the moldoscillator and a first strand guide segment are located within adetachable three-dimensional frame. This frame can be lifted andexchanged together with all its enclosures. At the same time the nextstrand guide segment located beneath is also accessible andexchangeable. According to the specifically described embodiment, themold with the mold table and the first strand guide segment areseparately located in the three-dimensional frame. This arrangement doesnot provide for automatic adjustment of the components to one another.Especially the alignment of the plane formed by the shaping inside wallof the mold and the generatrix (strand surface) to be put against therollers of the first strand guide segment is highly important due tothin strand shell and requires exact and laborious adjustment.

A continuous casting machine is known from AT-PS 347 057, where a moldand the foot roller stand attached to the mold on the exit side and abending zone connected downstream of the foot roller stand can bejointly dismantled from the continuous casting machine through asupporting frame comprising the mold and the bending zone.

This conception requires repeated adjustment of the individualcomponents to one another. One the one hand, the wall of the mold cavitymust be adjusted to the generatrix of the downstream foot rollers andthese foot rollers must be adjusted to the strand guide rollers of thesubsequent bending zone using an appropriate measuring ruler. On theother hand, how to adjust other components located in the mold area,such as the mold stirrer or the mold level measuring system, remainsunclear.

SUMMARY OF THE INVENTION

Accordingly, the technical problem of the invention is to avoid theaforementioned disadvantages and to form an assembly comprised of theknown components normally used in a continuous casting machine, i.e.mold, mold table, mold oscillator, downstream strand guide, possiblyadditional equipment such as mold stirrer and mold level measuringsystem, which allows short restranding times through the formation of asection-related machine unit and reduced maintenance expenditure throughthe modular design of the machine components.

This problem is solved by detachably integrating a first strand guidesegment preferably designed as foot roller stand in a second strandguide segment connected downstream and preferably designed as bendingzone and by supporting a mold stirrer on the second strand guidesegment. This arrangement has the special advantage that only the firstand second strand guide segments forming an assembly are to be adjustedin the workshop.

A particularly expedient embodiment results from designing the secondstrand guide segment in the area of the mold with raised supports whichare provided with bearing surfaces for the mold or the mold tablecarrying the mold and with fasteners, preferably hooks or lugs, for thecommon dismantling of the mold, mold stirrer and second strand guidesegment.

An improvement of the invention results from installing a mold levelmeasuring system, consisting of a radioactive source, preferably acobalt source, and a scintillation counter on the mold stirrer or on thesupports of the second strand guide segment. This arrangement allows toplace the mold level measuring system, which does not oscillate inresonance, very close to the mold cavity and thus to minimize thecapacity of the cobalt source while at the same time maintaining astable and clearly defined position for the mold level measuring system.

An especially stable continuous casting machine operating withoutmisalignment can be achieved by designing the mold oscillator asfour-eccentric oscillator with spring band steel guide.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the invention is explained in greater detail by meansof two figures, with FIG. 1 displaying a schematic longitudinal sectionthrough the continuous casting machine in the area of the mold and ofthe strand guide connected downstream and FIG. 2 illustrating adifferent section of the same embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The continuous casting machine is supported on stationary machinesupporting structure 1. Mold oscillator 3 which is comprised offour-eccentric oscillator 4 and spring band steel guide 5 is fixed onsupporting frame 2 of machine supporting structure 1. Mold oscillator 3is represented and described in detail in AT-PS 384 970. It is mainlycomprised of four eccentrics which are located in the corner areas ofsupporting frame 2 and driven by a common rotating drive, with therotating motion produced thereby being transformed into a verticaloscillating motion through short connecting rods. The connecting rods ofmold oscillator 3 are connected to frame-type mold table 6, whichabsorbs the oscillating motion and transfers it to mold 8. As can beseen from FIG. 2, spring band steel guide 5 is located between moldtable 6 and supporting frame 2 and mainly comprised of several springband steel guides 7 or comparable flexible elements whose ends arefixedly clamped to supporting frame 2 and whose central area isconnected to mold table 6. This arrangement ensures exact positioning ofthe oscillating machine parts in relation to the stationary machineparts, particularly the alignment of oscillating mold 8 in relation tostrand guide 9 which is supported on machine supporting structure 1.

Mold 8 is comprised of mold element 10 and portal-type mold frame 11 inwhich mold element 10 is inserted. Mold element 10 has a shaped cavitywhich corresponds to the section of the strand to be cast and consistsof a copper tube or copper plates as well as a backing structure withappropriate equipment for mold cooling.

In the direction of strand withdrawal, strand guide 9, which withdrawsand supports the hot strand, includes first strand guide segment 12 andsecond strand guide segment 13 which are connected downstream of mold 8.

First strand guide segment 12 is designed as framework in which severalrows of strand guide rollers 14 forming a closed cage are pivoted andforms an assembly that is detachably fixed in second strand guidesegment 13. Second strand guide segment 13 is designed as bipartiteframe, with outer bow frame 15 and inner bow frame 16 being providedwith strand guide rollers 14 and inner bow frame 16 being clamped toouter bow frame 15. Second strand guide segment 13 is supported onmachine supporting structure 1 through outer bow frame 15 with bearing17 and sliding bearing 18. Outer bow frame 15 with its strand guiderollers 14 moreover represents the reference side for adjusting thecontinuous casting machine.

Second strand guide segment 13 shows bearing surface 19 on which moldstirrer 20 is supported and is positioned at a distance from moldelement 10. In the area of the mold, second strand guide segment 13 isprovided with raised supports 21 with bearing surfaces 22, which engagewith mold 8 and mold frame 11, respectively, when second strand guidesegment 13 is dismantled, and which allows easy dismantling andinstallation of the common component comprised of mold 8, mold stirrer20, first strand guide segment 12 and second strand guide segment 13,which is referred to as section-related machine unit, within a shortrestranding time. According to an embodiment not represented, bearingsurfaces 22 can also be brought into engagement with mold table 6 duringinstallation or dismantling of the machine unit. Furthermore, raisedsupports 21 are provided with fasteners 27, which are designed as hooksor lugs and to which a hoisting gear is hinged for installation anddismantling purposes.

In order to be able to continuously check the level of the molten metalbath in mold 8, mold level measuring system 24, which does not oscillatein resonance and which is comprised of radioactive source 25 andscintillation counter 26, is installed on mold stirrer 20 in the area ofmold level 23. According to an embodiment not represented, radioactivesource 25 and scintillation counter 26 can be mounted to raised supports21.

In this arrangement of components of the continuous casting machine, theshaped cavity of mold 8 can be easily centered to strand guide rollers14 of strand guide segments 12, 13 connected downstream by means of ameasuring contact blade. The section-related machine head preset in thisway can be placed on mold table 6 and fixed without any furtheradjusting work.

Coolant for the mold is circulated through supply and discharge linesnot represented which lead through mold frame 11 and mold table 6 andwhich are automatically closed when mold 8 is placed on mold table 6.

What is claimed is:
 1. A continuous casting machine, comprising:a moldtable, a mold inserted on and supported on the mold table, a moldoscillator supporting the table and moving the table upon the moldoscillator oscillating; the mold having a downstream side where a strandexits the mold; a strand guide connected downstream of the mold; thestrand guide being comprised of a plurality of strand guide segments,and each strand guide segment including strand guide rolls for guidingthe strand downstream through the respective guide segment; a firststrand guide segment downstream of the mold comprising a foot rollerstand; a second strand guide segment downstream of the first strandguide segment, and the first strand guide segment being detachablyintegrated in the second strand guide segment; and a mold stirrersupported on the second strand guide segment for stirring the mold. 2.The continuous casting machine of claim 1, wherein the second guidesegment is shaped to define a bending zone for bending the strandpassing therethrough.
 3. The continuous casting machine of claim 1,further comprising a mold level measuring device comprising aradioactive source and a scintillation counter are installed on the moldstirrer.
 4. The continuous casting machine of claim 1, furthercomprising raised supports on the second guide segment extending up tothe area of the mold, the supports being provided with bearing surfacesfor positioning the mold and the mold table.
 5. The continuous castingmachine of claim 4, further comprising fasteners for common installationand dismantling of the mold, the mold stirrer and the second strandguide segment.
 6. The continuous casting machine of claim 4, furthercomprising a mold level measuring device comprising a radioactive sourceand a scintillation counter supported at the mold, wherein theradioactive source and the counter are installed at the supports of thesecond strand guide segment.
 7. The continuous casting machine of claim6, wherein the mold oscillator comprises four eccentric oscillators,each with a respective guide connected to the mold table.